Vol. L Sun— Cambrian Faunas of North China (iv) 37 



of the pygidium. Posterior margin with two backward pointing spines, next outer pair 

 only sUghtly longer. 



Surface pustulose under a strong lens. 



This species differs from B. cilix Walcott in the comparatively narrow frontal 

 limb, in the absence of distinct first and second glabellar furrows, in the pustulose charac- 

 ter of the surface, in the absence of the longitudinal ridge and in the conical terminal 

 portion and the comparatively uniform spinose character of the pygidium. 



Moreover, the facial suture cuts the front of fixed cheeks nearly at right angles, 

 being approximately parallel to the corresponding portion of the other suture, whereas 

 the facial suture of B. cilix cuts the fixed cheeks obliquely toward the anterior palpebral 

 lobe. 



This species is named after Mr. C. C. Tien in recognization of the fine collec- 

 tions made by him. 



Measurements: — ■ No. 520 

 Cranidium 



Length of cranidium 10.0 mm. 



Width of cranidium at the palpebral lobe ]0.0 mm. 



Length of glabella 6.5 mm. 



Length of frontal limb and rim 1 .6 mm. 



Width of occipital ring 1.6 mm. 

 Pygidium (Associated) 



Length ■ 10.5 mm. 



Anterior width of pygidium 18.0 mm. 



Horizon and Locality: — Late ^Middle Cambrian: from thin-bedded limestone of 

 Kushau horizon of Lin-Cheng, ChihU (Y. T. Chao and C. C. Tien Coll .). 



BlACKWELDERIA GIGAS Sun (sp. nov.) 

 Plate II, Figs. 8. 



One pygidium was obtained by the University Excursion from the Kushan for- 

 mation of Ku-Shan, Shantung. This is the largest pygidium of Blackw elder ia so far 

 found in China, and deserves to be designated by a separate name. 



Semicircular in outline, moderately convex, and with a spinose margin; axis 

 moderately convex, conical, tapering to its posterior end; it is divided by four clearly 



